The invention relates to a power supply device and an electronic apparatus using the same, and particularly to a power supply device which transmits large d.c. power and to a technique which is useful when applied to an electronic apparatus using this power supply device.
Such an electronic apparatus as a general purpose computer consumes a great deal of electric power, with its supply current ranging as large as several hundreds to several thousands amperes.
A technique for reducing the voltage drop on the current path between a d.c. power unit and a load, which is composed of power supply copper bars having a large current conducting capacity, is to decrease the length and increase the cross-sectional area of the copper bars, as disclosed in Japanese Patent Unexamined Publication No. 1-120098.
A method for reducing an a.c. noise which is propagated from a power unit to a load is generally known, as described in publication "Counter-Noise Measures for Electronic Equipment", pp. 82-85, published on Jun. 30, 1986 by Ohm Corp. In FIG. 3, the method is intended for a power supply circuit 103 in which a power source 101 which creates an a.c. noise voltage supplies power to a load 102 through a coupling impedance Zm, and an additional coupling impedance Zg being added in series to the Zm so as to increase the coupling impedance of the circuit 103, and also a bypass impedance Zb being added in parallel to the load 102 of the circuit 103 so as to reduce the a.c. noise that acts on the load 102.